Regulators of leukotactic mediators are present both in serum and in leukocytes. The former is purified by new, hydrophobic chromatographic methods and is being further characterized. Regulator substances present in leukocytes are being studied for release mechanisms (during phagocytosis) and for their relevance to kinase proteases present in lysosomal granule of leukocytes. BIBLIOGRAPHIC REFERENCES: Johnson, J. J., Anderson, T. P. and Ward, P.A. 1977. Suppression of immune complex-induced inflammation by the chemotactic factor inactivator. J. Clin. Invest. 59:951-958. Ward, P.A., Johnson, J.J. and Kreutzer, D.L. 1977. Abnormal regulation of leukotactic mediators. Am. J. Path. In press.